The effect of positive mood induction on reducing reinstatement fear: Relevance for long term outcomes of exposure therapy.

While exposure therapy is effective in treating anxiety, fear can return after exposure. Return of fear can be understood through mechanisms of extinction learning. One form of return of fear is reinstatement, or, the fear that results from an unsignaled unconditional stimulus (US) presentation after extinction. Though the conditional response (CR; e.g., fear) typically reduces during extinction, the excitatory conditional stimulus (CS+) valence remains negative. The more negative the CS+ valence after the end of extinction, the greater the fear at reinstatement. The current study evaluated the degree to which positive mood induction (positive imagery training; PIT) compared to control (positive verbal training; PVT) before extinction a) decreased CS+ negative valence during extinction and b) reduced reinstatement fear. Compared to PVT, PIT a) increased positive affect, b) decreased post-extinction CS+ negative valence, and c) reduced reinstatement responding as measured by eye blink startle reflex (when shock was used at reinstatement) and self-report fear (regardless of reinstatement US type). Results suggest that increasing positive affect prior to exposure therapy could reduce relapse through reinstatement.